Table 2.

Extent of thigh MRI findings among clinical subsets

	IMNM			IBM (n=153) Mean (SD)	PM (n=176) Mean (SD)	DM (n=219) Mean (SD)	CADM (n=17) Mean (SD)	Total (n=666) Mean (SD)
	Total (n=101) Mean (SD)	HMGCR (n=50) Mean (SD)	SRP (n=22) Mean (SD)
Oedema	55.5 (32.2)***	58.9 (31.8)	65.8 (28.9)	48.1 (24.6)***	29.4 (30.5)***	30.1 (36.7)***	6.1 (18.5)***	37.3 (33.5)
Atrophy	23.2 (28.7)**	21.7 (28.9)*	38.2 (30.2)*	32.2 (26.7)***	12.7 (24.6)*	5.7 (16.7)***	2.5 (7.4)*	16.2 (25.5)
Fatty replacement	38.0 (33.1)*	34.4 (30.9)	49.1 (31.2)	50.1 (27.3)***	28.3 (31.1)	17.5 (27.0)***	7.1 (12.8)**	30.7 (31.6)
Fascial oedema	6.2 (15.1)*	5.1 (15.2)	6.0 (12.2)	6.0 (12.0)**	5.8 (11.8)**	16.5 (24.3)***	8.6 (17.0)	9.5 (18.1)

Mean percentage of each major clinical group (IMNM, IBM, PM, DM and CADM) compared with the rest of the sample using Student’s t-test. In separate analyses, patients with anti-HMGCR and anti-SRP were compared to each other only.

^*<0.05;

^**<0.01;

^***<0.001.

CADM, clinically amyopathic dermatomyositis; DM, dermatomyositis; HMGCR, HMG-CoA reductase; IBM, inclusion body myositis; IMNM, immune-mediated necrotising myopathy; PM, polymyositis; SRP, signal recognition particle.